The subject of the invention is more precisely to detect any surface defects on a transparent or translucent object, such as wrinkles, washboards, load marks or neck ring flaws.
In the state of the art, a device is known to detect said defects comprising a diffuse light source which illuminates an object to be inspected. One or more cameras are arranged opposite the light source to collect the light flow transmitted through the object. Any defects in the object attenuate or deviate the transmitted light. These light variations are analysed to identify and detect defects. Said device is particularly adapted for visualizing and detecting inner defects on the side wall of the object. However, with said device it is not possible to visualize and detect minor, transparent surface defects.
Also, a technique is known, in particular through documents U.S. Pat. No. 5,637,864, or EP 1 118 854, which illuminates defects for their detection. However, this technique is not suitable for detecting surface defects that are transparent.